The Transition to PhD Research

STEPHEN REDDING

Princeton

April 7, 2020

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Introduction

• PhD Research is Hard— “If we knew what we were doing, it would not be called

research.” (Albert Einstein)

• Princeton’s core and field courses provide you with— Tools and techniques to do frontier economic research— Knowledge of the state of the art research

• Now is the time to look forward to your own research— This lecture talks about this transition and points the way

to some approaches and sources of information

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Introduction

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Introduction

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Research Questions Versus Topics

• A crucial distinction is between a research topic and aresearch question

• Writing and publishing papers is about identifyingcompelling research questions and answering them in aconvincing way

• Research Topic: A general area of interest that is definednarrowly enough to imagine becoming a local expert in it

– International trade and wage inequality– Foreign aid and economic development– The Great Recession and the Financial Crisis

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• Research Question: A problem that we do not know orunderstand, which puts some intellectual capital at stake,which has a well-defined answer, and where we have aresearch design that can convincingly answer the question

– What was the effect of the construction of the U.S. interstatehighway system on urban growth?

– Are there sufficient statistics in terms of empiricallyobservable moments for the welfare gains from trade?What is the class of models in which these sufficientstatistics hold?

– Can search and matching models account quantitatively forobserved levels of wage inequality?

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Finding Research Questions

• Research ideas (research questions) often come inunexpected ways, at unexpected times and fromunexpected sources

• But research ideas come to those who are looking for them• Often you will have many research ideas. Successful

research is about selecting the good ideas.– Time is finite and has an opportunity cost– Choosing what not to do is just as important as choosing

what to do

• What are some possible strategies for selecting researchideas?

• For more discussion, see The Craft of Research, by Wayne C.Booth, Gregory G. Colomb and Joseph M. Williams,University of Chicago Press

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• But research ideas come to those who are looking for them

• Often you will have many research ideas. Successfulresearch is about selecting the good ideas.

– Time is finite and has an opportunity cost– Choosing what not to do is just as important as choosing

what to do

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what to do

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what to do

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what to do

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Sources for Research Ideas

• Economist, Financial Times, popular books on economics,history, politics, sociology, the world around you

• Read the frontier papers in your field. Working through allthe math in those that interest you most can be very usefulfor getting ideas and learning new techniques and tricks

• Handbook chapters and surveys can be useful for getting asense of the boundaries of the research frontier

• But your research should not be driven by the literature.The research question should always come first

• What are the constraints that these frontier papers arebumping up against?

– How can you relax these constraints and extend theresearch frontier?

– How will relaxing these constraints change existing results?– What new results does relaxing these constraints offer?

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• Can you add an extra layer of microfoundations?– How will this extra layer change our understanding of

existing layers?

• But do not complicate just for the sake of complication.Models are about making simplifying assumptions toreveal key economic mechanisms

• What are the limitations of these frontier papers? How canyou improve on them?

• How do the research questions asked in these papers relateto popular economic discourse about the same issues?What are these papers missing? What research questionsare they overlooking?

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existing layers?

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existing layers?

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existing layers?

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Research Questions and Techniques

• Successful research is about asking compelling researchquestions and being able to answer them convincing

• Strong technical skills are important in being able toexamine new research questions and answer themconvincingly

• But do not focus on technical skills alone• There is relatively little job market payoff to applying

outstanding technical skills to irrelevant problems thatnobody cares about

• What matters is applying these outstanding technical skillsto convincingly answer compelling research questions

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• But do not focus on technical skills alone

• There is relatively little job market payoff to applyingoutstanding technical skills to irrelevant problems thatnobody cares about

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Research Design• What is the research question?

• What model/method/data are you going to use to answerthe question?

• What are the challenges in answering the researchquestion?

• How does your model/method/data overcome these?• What is new relative to existing research? New question,

better data, better model, better identification strategy?• Good theory delivers new results that are at first

surprising but become intuitive once one understands themodel. The whole should therefore be greater than thesum of the parts. Results should not follow too closelyfrom the assumptions

• Build the simplest model possible to capture thephenomenon that you are interested in. Abstract from theinessential to let the essential speak

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Research Design• What is the research question?• What model/method/data are you going to use to answer

the question?

• What are the challenges in answering the researchquestion?

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the question?• What are the challenges in answering the research

question?

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question?• How does your model/method/data overcome these?

• What is new relative to existing research? New question,better data, better model, better identification strategy?

• Good theory delivers new results that are at firstsurprising but become intuitive once one understands themodel. The whole should therefore be greater than thesum of the parts. Results should not follow too closelyfrom the assumptions

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question?• How does your model/method/data overcome these?• What is new relative to existing research? New question,

better data, better model, better identification strategy?

• Good theory delivers new results that are at firstsurprising but become intuitive once one understands themodel. The whole should therefore be greater than thesum of the parts. Results should not follow too closelyfrom the assumptions

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Research Design

• Once you have a research question, think about whatwould be the ideal research design to answer this question

• For example, in empirical research, this might ofteninvolve a randomized experiment

• If such an ideal research design is not available to you,how could you try to replicate the essential features of thisideal research design with the empirical data available?

• What sources of empirical variation could identify themechanism you are interested in?

• What natural experiments could provide such exogenousvariation?

• What instruments would satisfy the exclusion restriction ofonly affecting the outcome of interest through themechanism in question?

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Research Design

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Research Design

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Research Design

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Research Design

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Research Design

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What is a Compelling ResearchQuestion?

• What are your key new findings? What do we now knowabout the world that we did not know before?

• Why should we care about your findings? (So What?)?• Can you explain non-technically in two minutes to the

person on the Clapham Omnibus (or more importantly toan economist in another field) why they should care aboutyour findings?

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• Why should we care about your findings? (So What?)?

• Can you explain non-technically in two minutes to theperson on the Clapham Omnibus (or more importantly toan economist in another field) why they should care aboutyour findings?

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• Why should we care about your findings? (So What?)?• Can you explain non-technically in two minutes to the

person on the Clapham Omnibus (or more importantly toan economist in another field) why they should care aboutyour findings?

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The “So What” Question

• Do not underestimate the “So What?” question

– Do your findings help resolve a “puzzle”?– Do your findings help to decide which of several

competing views are correct?– Do your findings improve our estimates of a key elasticity

or coefficient?– Do your findings change our understanding of existing

questions that people care about? Do they suggest thatexisting research conclusions are wrong or need to beupdated?

– Do your findings have implications for policy?

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• Do not underestimate the “So What?” question– Do your findings help resolve a “puzzle”?

– Do your findings help to decide which of severalcompeting views are correct?

– Do your findings improve our estimates of a key elasticityor coefficient?

– Do your findings change our understanding of existingquestions that people care about? Do they suggest thatexisting research conclusions are wrong or need to beupdated?

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• Do not underestimate the “So What?” question– Do your findings help resolve a “puzzle”?– Do your findings help to decide which of several

competing views are correct?

– Do your findings improve our estimates of a key elasticityor coefficient?

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or coefficient?

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Persistence and Feedback

• Doing research is hard

• Do not give up too easily. Persistence is hugely important– Everyone encounters challenging problems during their

research– Successful research is often about working out ways

around these problems• Do not be too stubborn

– Research is typically not about working in isolation– Present your work and listen to feedback from your

advisers and colleagues– If all your advisors and colleagues are telling you

something, you will probably receive the same message onthe job market, so listen to what they are saying

• The final product is typically not the initial product– Research often involves many dead ends and the

reworking, revising and throwing away of material

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• Doing research is hard• Do not give up too easily. Persistence is hugely important

– Everyone encounters challenging problems during theirresearch

– Successful research is often about working out waysaround these problems

• Do not be too stubborn– Research is typically not about working in isolation– Present your work and listen to feedback from your

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Challenge Yourself

• Do not be afraid to address challenging research questions

• If you set your sights too low, you will not achieve verymuch

• At the same time, do not pose a research question that is sochallenging that you cannot answer it convincingly

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Challenge Yourself

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Challenge Yourself

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Research Advice• Keith Head from UBC has useful advice for research on his

web page• Jonathan Dingel from Chicago Booth has useful advice for

research on his web page• Jonathan’s advice for meeting with your adviser is

– Bring an agenda to meetings– 30-minute meetings are sufficient to discuss about three

substantive points in meaningful detail– Write up a page of notes beforehand to ensure that you

discuss those points– Follow through after meetings– At the beginning of a meeting, tell your adviser what you

did to implement or address concrete suggestions that shemade at the previous meeting

– After lunch workshop presentations in your field, followthrough in meeting with participants in those workshops toget their more detailed feedback

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Productivity Advice

• To make progress on your research– Working hard is a necessary condition for success– Plenty examples of incredibly intelligent people who are

not successful simply because they do not work hard– Other faculty members who appear brilliant are indeed

brilliant but they also work very hard

• Set aside time for research without distractions– No email, facebook or twitter– Switching between tasks is cognitively draining– You will be more productive if you focus on an important

task for a chunk of time (e.g. 25 minutes)

• Keep a work diary to see how you are spending your time

• The secret to making progress on important tasks isbuilding them into your daily and weekly routine

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Productivity Advice

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Productivity Advice

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Productivity Advice

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Productivity Advice

• The widely-acknowledge seminal book on productivity is– Getting Things Done by David Allen

• For more on the cognitive burden of distraction, see– Deep Work by Cal Newport

• For an interesting perspective on creativity, see– The Creative Habit: Learn It and Use It for Life by Twyla Tharp

and Mark Reiter

• Productivity Apps– Be focused

• For a broader perspective on designing your life– Designing Your Life: How to Build a Well-Lived, Joyful Life by

Bill Burnett and Dave Evans

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Job Market Placement Advice

• What can you do to improve your expected job marketoutcome?

– Create a brilliant piece of economic research– Write a stellar job market paper that effectively

communicates this economic research– Give a superlative job market presentation that effectively

communicates this economic research

• Write more papers– Learning by doing is a pervasive characteristic of much

human endeavor, so why not also for writing papers?

• Work as research assistants with faculty– Learn from seeing how faculty work and how they frame

and execute a research project– Research assistance can unexpectedly develop into

coauthorship through serendiptous idea creation

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Well-being Advice• Maintain a healthy work-life balance

– Too much stress and overwork reduces productivity– Make sure that you give yourself breaks and take vacation

to rest and recuperate– Productivity is achieved through consistent and sustainable

work habits and steady incremental progress

• Evidence that graduate school worldwide raisespsychological challenges

– Consistent and sustainable work habits are a goodmechanism for meeting these challenges

– Maintain friendships and activities outside research

• The university has a whole menu of resources available forimproving the graduate school experience

– McGraw Teaching & Learning Center (e.g. writing courses)– McCosh Health Center– Range of Counseling & Psychological Services (CPS)

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Research Suggestions

• For various suggestions on how to approach research, seefor example the articles in Passion and Craft: Economists atWork (editor Michael Szenberg) by:

– Avinash Dixit– Claudia Goldin– Elhanan Helpman– Hal Varian– And a number of other illustrious economists

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Paul Krugman’s Four Rules

• “Listen to the gentiles”– Pay attention to what intelligent people are saying, even if

they do not have your customs or speak your analyticallanguage

• Question the question

– If people in a field have got bogged down on questions thatseem very hard, it is a good idea to ask whether they arereally working on the right questions. Often some otherquestion is not only easier to answer but actually moreinteresting

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• “Listen to the gentiles”– Pay attention to what intelligent people are saying, even if

they do not have your customs or speak your analyticallanguage

• Question the question– If people in a field have got bogged down on questions that

seem very hard, it is a good idea to ask whether they arereally working on the right questions. Often some otherquestion is not only easier to answer but actually moreinteresting

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• Dare to be silly– All models are abstractions and involve silly assumptions– If a new set of assumptions seems to yield a valuable set of

insights then these assumptions may be useful

• Simplify, simplify– Express your ideas in the simplest possible model. The act

of stripping down to this minimalist model will force youto get to the essence of what you are trying to say (and willalso make obvious those situations in which you actuallyhave nothing to say). And this minimalist model will thenbe easy to explain to other economists as well

– Once you understand the mechanisms, you can alwaysenrich the model later, as for example when taking it to thedata quantitatively

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• Dare to be silly– All models are abstractions and involve silly assumptions– If a new set of assumptions seems to yield a valuable set of

insights then these assumptions may be useful

• Simplify, simplify– Express your ideas in the simplest possible model. The act

of stripping down to this minimalist model will force youto get to the essence of what you are trying to say (and willalso make obvious those situations in which you actuallyhave nothing to say). And this minimalist model will thenbe easy to explain to other economists as well

– Once you understand the mechanisms, you can alwaysenrich the model later, as for example when taking it to thedata quantitatively

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Rules for Code and DataMatt Gentzkow and Jesse Shapiro

• See Code and Data for the Social Sciences: A Practitioner’sGuide, available on my website throughout the material fortrade PhD students link

– Automation– Version Control– Directories– Keys– Abstraction– Documentation– Management

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Rules for WritingClaudia Goldin and Larry Katz

• Rule 1: Most people do not have a Nobel Prize winningidea.

– It is always possible to transform a good idea into a greatpaper and a superb presentation.

– Even if your idea is Nobel-worthy, you can always make itinto a poorly written paper and a lousy presentation.

• Rule 2: The insights of your paper will first be judged byhow you present them. If your paper is written in anunprofessional manner, your empirical work,mathematical proofs, and models will be viewed withinitial skepticism.

• Rule 3: Your paper is an exercise in persuasion (we meanin positive not normative economics). Your readers areyour audience. They have better things to do than readyour paper. Make them interested in your thesis andconvinced of your argument.

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• Rule 4: No great paper – no matter how well constructed,brilliant, and well written – first emerged from the authorsprinter in that form. It was rewritten at least 10 times.Rewriting is the true art of writing.

• Rule 5: No author – no matter how careful and humble –can see all (or even most) of his or her writing errors. Tradepapers with another student. Be tough; there will be someinitial pain, but gratitude will follow.

• Rule 6: Most paragraphs have too many sentences andmost sentences have too many words. Repetition is boring.We repeat: repetition is boring. Cut, cut, and then cutagain.

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• Rule 7: The “foot-in-the-door” parts of your written workare the abstract and introduction. Write them clearly andconcisely. The abstract is not simply the first paragraph ofyour paper (or the last paragraph for that matter). Writethem so that they are accessible by any intelligenteconomist, not just those in your field.

• Rule 8: Verbalizing your argument is more difficult thanwriting it. Giving a presentation will reveal where yourargument falls flat and will show you how to redraft thepaper. Give many presentations before sending out yourpaper. Give them to a workshop, friends, a dog or cat,even the wall. The presentation will force you to confrontinconsistencies in your argument.

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• Rule 9: Be your own worst enemy. If you won’t, someoneelse will.

• Rule 10: There are many other rules. We cannot cover all ofthem. Consult good style guides and guides to writing ineconomics

– Some recommendations in such style guides are subjective,but at least use them to think carefully about what you aredoing

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Guides to Writing in Economics

• The Little Book of Research Writing by Varanya Chaubey

• Economical Writing (2nd edition, Waveland Press) byDeirdre McCloskey (Economics, Rhetoric, Philosophy,University of Illinois, Chicago)

– Opinionated and subjective but much (though not all) ofthe advice is very good

• A Guide for the Young Economist (M.I.T. Press, 2001) byWilliam Thomson (Economics, University of Rochester)

• See also, William Thomson, “The Young Persons Guide toWriting Economic Theory,” Journal of Economic Literature,37, March, 1999, 157-83.

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Presentation Guides

• Better Presentations: A Guide for Scholars, Researchers, andWonks by Jonathan Schwabish

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Style Guides

• The Elements of Style, by William Strunk Jr. and E. B. White– The classic guide to writing effectively

• A Manual for Writers of Research Papers, Theses, andDissertations, by Kate L. Turabian, University of ChicagoPress

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Style Reference Books

• The Chicago Manual of Style, University of Chicago Press– A classic reference point

• Fowler’s Modern English Usage, by H. W. Fowler, OxfordUniversity Press

– Dated and from another era, but the ultimate classicreference book on the English language

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Research Suggestions

• For an excellent discussion of the nature of research, see:– The Craft of Research, by Wayne C. Booth, Gregory G.

Colomb and Joseph M. Williams, University of ChicagoPress

• For the suggestions of several illustrious economists onhow to approach research, see:

– Passion and Craft: Economists at Work, edited by MichaelSzenberg, Michigan University Press

• For a subjective but stimulating discussion of approachesto empirical research, see

– Mostly Harmless Econometrics: An Empiricist’s Companion byJoshua D. Angrist and Jorn-Steffen Pischke

• For a more structural approach, see– The Limits of Inference without Theory, by Kenneth I. Wolpin

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